Optical stack comprising adhesive

An optical stack comprising a first optical film comprising a plurality of structures comprising an optically active portion designed primarily to provide optical gain and an optically in-active bonding portion disposed on a first surface wherein the optically in-active portion of the structures is bonded to a second optical film with a light-transmissive adhesive layer such that a portion of the structures penetrate the adhesive layer and a separation is provided between the adhesive layer and the first surface, wherein the adhesive layer comprises an interpenetrating network of the reaction product of a polyacrylate component and a polymerizable monomer having functional groups and a molecular weight less than 150 g/mole per functional group, the peel strength of the optical stack is at least 50 grams force/inch and the stack exhibits a decrease in optical gain of no greater than 5% when the optical stack is conditioned at 65° C. and 95% relative humidity for 200 hours.